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charset="utf-8" X-RootMTR: 20260807182023eucas1p1f653436207b2b00338e99ea1d8f847df X-EPHeader: CA X-CMS-RootMailID: 20260807182023eucas1p1f653436207b2b00338e99ea1d8f847df References: <20260717180442.110954-18-aneesh.kumar@kernel.org> <20260807092612.2202005-1-aneesh.kumar@kernel.org> <20260807135810.GA200537@ziepe.ca> <20260807164734.GE200537@ziepe.ca> <20260807182017.GH200537@ziepe.ca> On 07.08.2026 20:20, Jason Gunthorpe wrote: > On Fri, Aug 07, 2026 at 06:13:49PM +0000, Mostafa Saleh wrote: >> But the whole thing is best effort anyway, the kernel picks >> IO_TLB_DEFAULT_SIZE which does not depend on the system topology or >> how many devices or how much DMA they do. >> SWIOTLB memory is wasted if unused so we should be careful around >> that as it would be the other way around and users would have to >> decrease it manually. > Yeah, it is why the arch code shouldn't really be sizing it directly, > it should be done in common code and, yes, we are probably going to > have to do something alot smarter to have the common code better > auto-tune this for the CC case.. What about the $subject patch? I assume that it is still needed to restore the behavior that was altered by the "[PATCH v8 00/23] dma-mapping: Track shared DMA state through direct, pool and swiotlb paths?" patchset? Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland